As is known, a transmission belt drives an outer crown of a pulley alternator, driving an internal hub. This pulley is subject to speed and torque variations in service, mainly due to the engine acyclisms. There are different ways to smooth the said variations exerted on the pulley, for example by providing a one-way clutch between the hub and the pulley crown. In one rotation direction, the one-way clutch transmits a torque from the hub to the pulley crown while in the other rotation direction the pulley operates as freewheel.
The said pulley crown is generally made in metal and is rotationally supported by at least one rolling bearing comprising an inner ring, an outer ring and rolling elements between the said rings, the said rolling bearing parts being made in metal. The rotation transmission device comprising such elements has a weight generating an important inertia.
Moreover, a metallic pulley crown necessitates thermal coatings for preventing corrosion or improving the hardness, for example. Such surface treatments are expensive and increase the rotation transmission device manufacturing cost.
It is therefore a particular object of the present invention to overcome these aforementioned drawbacks by providing a rotation transmission device of simple design that is easy to assemble, economical, able to operate for a long time in both an effective and an economic manner.